1. Field of the Invention
The invention relates to machine tool systems, such as machining centers, mills, and lathes. More particularly, the field of the invention involves mechanisms for replacing the tool and its associated holder in the spindle of a machine tool system.
2. Background Art
A typical computer numerically controlled (CNC) machine tool system includes a machining center having a tool changing mechanism. The mechanism removes a particular tool, including its respective holder, from the machining spindle and replaces it with a different tool and holder. With machining centers of this type, a plurality of machining operations is conducted, which can require a like number of different tools be positioned in the spindle. Thus, prior machining systems have included a plurality of tools available for on-demand usage.
In the development of modern machining centers, considerable focus has been placed on the tool changing mechanism, i.e., the device that extracts a particular tool and holder from the rack and places it within the operating spindle at the machining location. For instance, the automatic tool changer of U.S. Pat. No. 3,844,028 (Hague et al.) is exemplary of such automatic tool changing mechanisms.
The tools may be provided in a variety of forms. Typically, the tools are mounted on a movable component that is integrated into the numeral control system of the machining center. The movable component can then be controlled to move a desired tool to a pre-determined location to be extracted by the automatic tool changing mechanism. This type of tool storage and retrieval mechanism is shown in FIG. 1. In particular, magazine 10 includes a plurality of tool pockets 12 that are configured to firmly grasp a tool holder. Magazine 10 is a chain type mechanism in which tool pockets 12 are interconnected by drive chain 14, or similar pocket positioning mechanism, which is wound around hub 15 and is driven by a motor (not shown) under direction of the numeric control system or a manual system. In operation, drive chain 14 can be incrementally driven to position a specific tool pocket 12 at the tool changing location. Magazine 10 also includes housing 17 that surrounds and supports tool pockets 12, drive chain 14 and hub 15. FIG. 2 presents magazine 10 as it is connected and arranged with machining center 11.
The present invention is a tool changer with a movable arm that removes and inserts a tool from a stationary tool rack into the spindle of a machining center.
According to the present invention, the tool changer comprises a tool rack having a plurality of locations for holding tools, and an arm structured and arranged to be movable between the plurality of locations including a position which is capable of accessing a spindle of the machining center. Each of the locations further comprises a fork that has a plurality of prongs. The movable arm has two grippers, wherein one of the two grippers is disposed at an angle of about 90xc2x0 relative to the other of the two grippers.
The present invention provides a tool changer for removal and installation of tools in a machining center having a spindle for holding a tool, including a tool rack having a plurality of locations for holding tools and a rotatable arm movable between the spindle and the plurality of locations. Each of the plurality of locations has a clip for holding a tool and each clip has two arms with the arm on a first side of the clip having an inclined surface. The rotatable arm includes at least two grippers with each gripper defining at least one cam surface, the cam surface being structured and arranged to engage the inclined surface of the clip to allow for at least of insertion and removal of a tool in the clip.
The present invention further provides a machining center including a machine having a spindle holding one of a plurality of tools, and a tool changer for removal and installation of the plurality of tools in the machine. The tool changer includes a tool rack having a plurality of locations, and a rotatable arm movable between the spindle and the plurality of locations. Each location holds a tool and has a clip for holding a tool with each clip having two arms and the arm on a first side of the clip having an inclined surface. The rotatable arm includes at least two grippers with each gripper defining at least one cam surface, the cam surface being structured and arranged to engage the inclined surface of the clip to allow for at least one of insertion and removal of a tool in the clip.
The present invention further provides a method of changing tools in a machining center having a tool changer with a rotatable arm for removing and placing tools in a spindle of a machine or a tool rack having locations for holding tools including providing at least two grippers on the rotatable arm with the grippers defining a cam surface, providing a tool holding device at each location on the tool rack with the tool holding device including two arms with one of the arms having an inclined surface, moving one of the grippers into engagement with the tool holding device, engaging the tool holding device arm having the inclined surface with the cam surface of the gripper, unlocking the tool holding device, and disengaging the tool holding device arm having the inclined surface from the cam surface of the gripper.
An advantage of the present invention is that the tool changer is more reliable than prior tool changers because of fewer parts in its assembly.
An advantage of the present invention is that the tool changer is lightweight and compact for handling and easy to adapt to a machining center with limited space.
Another advantage of the present invention is the faster time to change a tool in the spindle.
Another advantage of the present invention is that more tool racks may be easily added to the tool changer, therefore providing more tool storage and a larger variety of changing capability.
Other advantages and benefits of the invention can be readily discerned from the following written description and accompanying figures.